Move scroll event handlers from layer to layer tree view.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 2489 matching lines @@
         DCHECK_GT(status.main_thread_scrolling_reasons,
                   MainThreadScrollingReason::kMaxNonTransientScrollingReasons);
       }
 
       *scroll_on_main_thread = true;
       *main_thread_scrolling_reasons = status.main_thread_scrolling_reasons;
       return NULL;
     }
 
     if (optional_has_ancestor_scroll_handler &&
-        scroll_layer_impl->have_scroll_event_handlers())
+        scroll_layer_impl->layer_tree_impl()->have_scroll_event_handlers())
       *optional_has_ancestor_scroll_handler = true;

[aelias_OOO_until_Jul13, 2016/01/28 22:25:07]

Please delete this parameter, and instead in LayerTreeImpl::ScrollBegin,
directly do "scroll_affects_scroll_handler_ =
active_tree()->have_scroll_event_handlers();"

[dtapuska, 2016/01/29 21:23:34]

Done.

 
     if (status.thread == InputHandler::SCROLL_ON_IMPL_THREAD &&
         !potentially_scrolling_layer_impl) {
       potentially_scrolling_layer_impl = scroll_layer_impl;
     }
   }
 
   // Falling back to the root scroll layer ensures generation of root overscroll
   // notifications while preventing scroll updates from being unintentionally
   // forwarded to the main thread. The inner viewport layer represents the
@@ skipping 1369 matching lines @@
   return task_runner_provider_->HasImplThread();
 }
 
 bool LayerTreeHostImpl::CommitToActiveTree() const {
   // In single threaded mode we skip the pending tree and commit directly to the
   // active tree.
   return !task_runner_provider_->HasImplThread();
 }
 
 }  // namespace cc